debian's service provider has some issues if the script is absent, we can workaround this problem using the trick of this patch

manifests/disable.pp

@@ -1,12 +1,7 @@
+# remove postfix
 class postfix::disable {
-
-  service{'postfix':
-    ensure => stopped,
-    enable => false,
+  case $::operatingsystem {
+    debian: { include postfix::disable::debian }
+    default: { include postfix::disable::base }
   }
-  package{'postfix':
-    ensure => absent,
-    require => Service['postfix'],
-  }
-
 }

manifests/disable/base.pp

@@ -0,0 +1,12 @@
+class postfix::disable::base {
+
+  service{'postfix':
+    ensure => stopped,
+    enable => false,
+  }
+  package{'postfix':
+    ensure => absent,
+    require => Service['postfix'],
+  }
+
+}

manifests/disable/debian.pp

@@ -0,0 +1,7 @@
+# debian has some issues with absent
+# init scripts
+class postfix::disable::debian inherits postfix::disable::base {
+  Service['postfix']{
+    hasstatus => false,
+  }
+}